Sandbox c10

 1ACJ shows the crystal structure of Torpedo californica acetylcholinesterase (TcAChE) complexed with tacrine.

Tacrine is a parasympathomimetic and a centrally acting cholinesterase inhibitor.

It was the first centrally-acting cholinesterase inhibitor approved for the treatment of Alzheimer's disease.

Tacrine’s ring is stacked between the aromatic rings of tryptophan 84 and phenylalanine 330 (W84 and F330).

Harel M, Schalk I, Ehret-Sabatier L, Bouet F, Goeldner M, Hirth C, Axelsen PH, Silman I, Sussman JL. Quaternary ligand binding to aromatic residues in the active-site gorge of acetylcholinesterase. Proc Natl Acad Sci U S A. 1993 Oct 1;90(19):9031-5. PMID:8415649 TextToBeDisplayed Hemoglobin (Hb), also spelled haemoglobin, (see on the right a three-dimensional representation of a single molecule) is the protein that carries oxygen from the lungs to the tissues where it's needed. The carbon dioxide produced by the consumption of oxygen. In order to function most efficiently, hemoglobin needs to bind to oxygen tightly in the oxygen-rich atmosphere of the lungs and be able to release oxygen rapidly in the relatively oxygen-poor environment of the tissues. It does this in a most elegant and intricately coordinated way.